Field devices for measuring physical quantities in industrial plants frequently comprise a controller that comprises an electronic processor by means of which a sensor of the field device may be controlled, and an acquired measured value of the physical quantity may be further processed. In this arrangement the corresponding system software is as a rule stored in a non-volatile memory in the controller.
Certain types of field devices are designed to become active only at defined points in time and, for example, to carry out a measurement. In this manner energy may be saved that possibly only may be provided by a battery. Before each measurement process the field device is then started and the controller carries out a boot routine that also includes checking the memory in order to check that in the meantime the system software has not been corrupted.
In order to check the memory a cyclic redundancy check, CRC, may be carried out. As a rule this is very time-consuming and the system start takes a correspondingly long time.